Rotary kiln construction



July 2 1 1959 F. J. ANDERSON w2,895,725

ROTARY 'KILN oNsTRUcTIoN 2 Sheets-Sheet 1 Filed Deo. 26, 1956 frana/gy,

F. .1.A ANDERSON 2,895,725 ROTARY KILN CONSTRUCTION July 2l, 195,9

2 Sheets-Sheet 2 Filed DBC. 26, 1956 INVENTOR.

lfm/Quia Patented July 21, 1959 ROTARY KILN CONSTRUCTION Frank J.Anderson, Laramie, Wyo., assignor to Monolith Portland Midwest Company,Los Angeles, Calif., a corporation of Nevada Application December 26,1956, Serial No. 630,618

16 Claims. (Cl. 263-33) This invention relates to new and improvedrotary kiln construction. This application is a continuation-in-part ofa co-pending application Serial No. 486,227 tiled February 4, 1955, nowabandoned entitled, Kiln Construction.

Rotary kilns are conventionally utilized in a large number of industriesfor a variety of purposes. In certain industries such as, for example,the cement industry, such rotary kilns are constructed out of acylindrical metal shell. Within such a shell there is normally located abrick lining serving to protect the shell proper from the action of heatgenerated in the kiln during various operations such as, for example,sintering cement. Kilns of this category are conventionally mounted sothat the axis of the kiln shell is located at a slight angle to thehorizontal. With this type of mounting material Will flow or travelthrough the kiln from the upper end of it to the lower end of it as thekiln shell is rotated.

Because it is extremely expensive to replace the brick lining in rotarykilns of the class indicated in the preceding paragraph, it is importantthat these linings be con- -structed in such a manner so as to last aslong as possible during use. In order to provide brick linings whichwill not fail in a short period of time, a number of different types ofkiln lining constructions have been suggested. One of the methods is toattach to the individual bricks forming a kiln lining various metalshims which extend along the sides of the brick so as to be either incontact with or in very close proximity to the metal shell in a rotarykiln. These shims are-not considered to be completely satisfactory inprolonging the life of a rotary kiln lining. They serve to conduct undueamount of heat from the interior of the kiln to the metal shell. Thistends to result in a number of things. One of these is that heat isremoved from Within a rotary kiln during the use of this kiln, andhence, the removed heat is not available to do work within the kiln.Another of these items is that heat conveyed to the rotary kiln shelltends to result in the shell becoming unduly hot. This, of course, iswhat a lining is installed in a rotary kiln to avoid.

Another suggested method for prolonging the effective life of a liningwithin a rotary kiln involves the use of layers of different types ofbrick. ln one example of this type of structure layers of acid and basicbrick are placed in contact with one another within a rotary kiln shell.Laminated structures of this category have been proposed in which thelayers of brick used are attached to one another so as to be capable ofbeing handled as a single brick and in which metal shims are used inconjunction vvith such laminated brick structures. Constructions of thistype are not considered to be acceptable for a number of reasons. Sincetwo types of bricks are employed they are comparatively expensive.Further, different types of brick differ from one another in bothchemical and physical properties. As a result the bond which may becreated between ditferent types of brick after slight use.

It is an object of this invention to provide rotary kiln constructionswhich are not subject to the various disadvantages and limitations ofthe various prior art constructions broadly indicated in the precedingdiscussion, and which are not subject to the various disadvantages andlimitations of other related constructions. Afurther object of thisinvention is to provide new and improved brick linings for rotary kilnswhich are capable of comparatively long use. A related object of theinvention is to prolong the life of brick linings for rotary kilns bymeans of devices or members which are applied to and used in conjunctionwith brick so as to strengthen the same and so as to reduce the Wear onthem. With the constructions of this invention specially shaped metalshims as will hereinafter be described are employed so as to hold thebricks in a rotary kiln in place. These metal shims serve a number offunctions in preserving the rigidity and shape of a complete kilnstructure, in prel venting and inhibiting cracks, and in preventingundue loss of heat to the exterior of a rotary kiln, and these shims mayhave the shape of either segments of a circle or ring of any desiredlength or of a complete circle. Other objects and advantages of theinvention will be more fully apparent from the remainder of thisdescription, including the appended claims and the' accompanyingdrawings in which:

Fig. 1 is a cross-sectional View of a rotary kiln constructed inaccordance with this invention;

Fig. 2 is a partial cross-sectional view taken at line 2 2 of Fig. 1;

Fig. 3 is a perspective view of a metal shim employed in the kiln shownin Fig. 1;

Fig. 4 is a perspective view of a modified metal shim capable of beingemployed with the invention;

Fig. 5 is a perspective view of another modied metal shim capable ofbeing employed with the invention;

Fig. 6 is a cross-sectional view similar to Fig. 1 of a further modiedstructure of this invention;

Fig. 7 is a cross-sectional view taken at line 7-7 of Fig. 6;

Fig. 8 is a cross-sectional view similar to Fig. 7 of still a furthermodified construction of this invention;

Fig. 9 is a perspective View of the modified metal shim of theinvention;

Fig. l0 is a cross-sectional View similar to Fig. 2 of a modiedstructure utilizing the shims shown in Fig. 9; and

Fig. 11 is a partial cross-sectional view taken at line 11-11 of Fig.10.

In all figures of the drawings like numerals are used to designate likeparts whenever convenient for purposes of illustration and explanation.The accompanying drawings are not to be taken as limiting this inventionin any respect. Thoseskilled in the art to which this invention pertainswill realize that these drawings are primarily intended so as to clearlydesignate the preferred nature of this invention. Obviously thedimensions and/or relative sizes of the various parts in theconstructions shown can be changed so as to adapt the invention for usein various sizes of rotary kilns and with various types and sizes ofbricks.

In order to understand the invention it may be stated in essentiallysummary form that it involves rotary kilns which are formed so as toinclude: a cylindrical metal shell; and a lining located within theshell, this lining being composed of courses of brick between whichthere are positioned specially formed metal shims. The actual details ofthis invention are more fully and precisely set forth in what may beconsidered a summary form in the appended claims.

In Figs. 1 and 2 of the drawings there is shown a rotary .kiln 10 ofknown4 exterior construction which is formedso as to include a metalshell 12 serving to hold a brick lining 14 consisting of a plurality ofrows or courses of brick 16 located in planes transverse orperpendicular to the axis of the shell 12. This lining 14 is composed ofindividual, conventional bricks 18, each of which is formed in aconventional manner out of a single composition so as to have a uniformphysical and chemical composition throughout. These bricks may be of anyknown common variety. Thus, they may be either acid or basic incategory. It is, of course, preferred that the brick 16 be refractory incharacter for use in a rotary kiln.

Between the courses of brick 16 there are located metal shims 20 each ofwhich is formed as indicated in Fig. 3 of the drawings. Each of themetal shims 20 is manufactured so as to include inner and outer edges 22and 24 which are preferably shaped as arcs of different circles having acommon center located at the center of the kiln 10. These shims 20 alsohave side edges 26. Along the interior edges 22 of the shims 20 thereare located adjacent to the ends of the shim 20 small flanges 28 whichserve during the placement of the brick lining 14 to hold the shims 20so that the outer edges 24 are spaced from the metal shell 12 byengaging the bricks 18.

The distance from the outer edges 24 of the shims 20 to the metal shell12 may be varied to a considerable extent. These outer edges 24 arelocated far enough in the shell 12 so that no heat is directly conductedfrom the shims 20 to the shell 12 during the operation and use of thekiln 20. Effective results have been achieved with this distance beingabout one inch. The shims 20 should be spaced far enough from the shell12 so that the conductivity of heat to the shell through the areaoccupied by the shims 20 is not appreciably different from theconductivity of heat through an equivalent area of bricks 18 to theshell 12. It is presently preferred that the heat conducted through thearea occupied by the shims 20 to the shell 12 be not greater than theheat conducted through an equivalent area of the bricks' 18 to thisshell. The shims 20 are preferably of such a length as to extend along anumber of individual bricks 18 within the courses 16. In the embodimentof the invention illustrated in Fig. 1 these shims 20 extend around thecenter of the shell 12 along an arc for approximately 30 of a circle.The length of these shims may, however, be changed as desired, dependingupon various Vconditions such as the length yof metal strips availablefrom which to cut the actual shims 20. With the preferred constructionof the invention the shims extend along a course of brick the length ofat least two bricks. The shims 20 may be formed so as to have anydesired length. Thus, they can even be formed so as to have the shape ofa ring extending completely around the interior of a kiln. When soformed they may be held in place by any of the means indicated in thisspecification.

The shims 20 are preferably located within the shell 12 in such a mannerthat the adjacent side edges 26 are positioned or staggered in anirregular manner throughout the length of the metal shell 12, asillustrated in Figs. 1 and 2 of the drawings. It is also preferred thatthese adjacent edges 26 be located not at the junction between twobricks in order to achieve maximum reinforcement. This staggeredplacement of the shims 26 serves to tend to prevent cracks fromdeveloping within the brick lining 14 and serves to prevent such crackstravelling from one of the courses of brick 16 to another of the coursesof brick. Similar results can be noted without this staggered placement,but'these results are not considered to be a's pronounced as with thestaggered placement described.

It will be realized in the aforegoing that the spacing of the outeredges 24 from the metal shell 12 results in a structure in which theshims 20 do not convey orconduct heat directly to this metal shell. Thisis advantageous inasmuch as it is normally desired when operating a'rotary kiln to maintain nearly as much heat as possible within the kilnso that such heat may be effective in promoting desired effects withinthe material being treated in a. kiln.

However, some loss of heat from within the interior of a rotary kiln isnecessary in order that the interior portion of a kiln lining does notburn up. The structure shown and described here permits a restrictedloss of heat to a kiln shell through the bricks employed so that theexposed surface of this lining is not damaged by overheating. With thisstructure the brick within a kiln is capable of absorbing and holding,and transferring to a load within a kiln suicient heat so as to operateas an effective heat exchange media as a kiln rotates. It will berealized that for heat control alone the length of the shims 20 isunimportant; the spacing of the shims from the kiln is responsible forthese shims not conveying heat to the kiln shell. With the constructionshown the shims 20, and the other shims hereinafter described are allregularly and uniformly spaced from the kiln shell.

The shims 20 also serve a number of other functions. As the kiln 10 isoperated in a conventional manner the individual courses of brick tendto move or creep slightly toward the lower end of the kiln so that allof the bricks 18 are wedged in place. Such bricks are, of course,tightly wedged in place during installation. With the structures of theinvention the metal shims 20 are edged between the individual courses16. These shims bear against the individual bricks 18 in such a mannerthat a high frictional force is developed which [tends to preventmovement of the individual bricks 13 since these individual bricks areinterconnected by the shims 20.

It will be realized from this that the shims 20 aid in maintaining arigid lining structure which is relatively immune to cracking. It willbe further realized that the factor termed kiln circularity is thusimproved by the shims 20. Because of the rigid structure developed thetendency of the lining 14 to distort from other than a circular shapeduring the operation of the kiln 10 is effectively combatted with theshims 2t). Since movement of the bricks 18 caused by such distoltion ofa rotary kiln in use has the effect of shortening the life of a bricklining the shims 20 aid in the maintenance of a rigid structure and inprolonging the life of a kiln lining.

The reinforcement of the kiln lining 14 by the shims 20 is considered tobe primarily the result of the principal portions of these shimsextending across the joints between individual bricks 18. In use theprincipal portions of the shims 20 serve to hold the lining 14 againstmovement because of the strength in these members. This strength isconsidered to be independent of the spacing of the principal portions ofthe shims 2t) away from the kiln shell 12, although such spacing isemployed so as to obtain the complete advantages of the invention.

Since the strength of the shims 29 is important, it is preferred to formthese shims out of sheet steel or iron because such material canwithstand the conditions normally encountered when located as shown.Various equivalent metals or alloys can, of course, be employed. Duringthe use of a kiln such as the kiln 1) reactions normally take placebetween the shims employed and the adjacent brick; also reactionsbetween these members and the material treated within this kiln arenormally apparent. Such reactions are commonly stated to lead to theformation of what may be termed eutectic mixtures and to the formationof certain specific composites. It has been found in practice that theprincipal portion of shims such as the shims 20 are not so reacted underthe normal operating conditions in the cement industry; and, hence,remain in their initial form between the courses of brick so as `toreinforce the lining within a rotary kiln. Some reinforcement isobtained when the shims employed are relatively short; however, greaterreinforcement occurs when shims of a comparatively long length asindicated in the preceding are employed, since large shims serve todistribute various stresses and strains encountered over a comparativelylarge area so that comparatively minor stresses and strains which wouldlead to cracking of the lining within a conventional kiln will in effectbe absorbed so as not to lead to cracking.

Itis possible to modify the shim construction illustrated in Figs. l and2 of the drawings in a number of ways. Obviously the anges 28 may bereplaced by a number of different equivalent structures. What are ineffect flanges have been created from shims formed out of at sheet ironby the simple expedient of welding small washers or rods to the interioredges 22 of such shims. It is not necessary that the shims 20 bemanufactured so that the inner and outer edges 22 and `24 have differentradii, although this is preferred since theoretically best heat controlcan be obtained with a symmetrical structure. For commercial reasons itis frequently desired to cut the shims 20 out of a single at sheet ofsteel. When this is done, it is possible to form both the inner andouter edges 22 and 24 so that bothof these edges have the same radii.This does not prove disadvantageous so long as the outer edge 24 of ashim 20 is manufactured of such a dimension as to be spaced from themetal shell 12 of a rotary kiln within which it is to be installed.

It is also possible to modify the shim 20 in a wide variety of otherways. In Fig. 4 of the drawings there is shown a metal shim 30 which hasinner and outer edges 32 and 34 corresponding to the edges 22 and 24.With this construction the outer edge 34 is designed to bear directlyagainst the metal shell of a rotary kiln. In order to provide theeffective heat control which is necessary with this invention thesection of the shim 30 adjacent to the outer edge 24 is provided with aseries of perforations 36. Thus, the shim 30 is formed so that its outerportion is essentially of a Swiss-cheese like structure. Obviously suchholes as the perforations 36 act to provide an insulating effect so thatthe principal portion of the shim 30 is spaced on the interior of arotary kiln. The shim 30 cannot, because of the small cross sectionalarea of metal available for conducting heat to the outer edge 34, serveto conduct any great material amount of heat to the metal shell of arotary kiln. The principal portion of this shim 36 is designed so as tobe spaced from the shell of a rotary kiln so as to provide effectivereinforcement as previously indicated. It should be specically notedthat the perforated structure of the shims 30 is advantageous indeveloping a high degree of frictional force between the adjacent rowsor courses of brick in a rotary kiln because of the irregularity of theshape of this shim 30.

The advantages of the invention can also be obtained utilizing a metalshim 40 substantially as shown in Fig. 5. This metal shim has interiorand outer edges 42 and 44 which also correspond in shape to the edges 22and 24.

From the outer edges 44 there project small extensions 46 which normallyrest against the outer metal shell of a rotary kiln in order to space orposition the principal portion of the shim 48 within the interior of thekiln. Here again, as with the shim 38, only a very small amount of metalis available to conduct heat directly to the shell of the rotary kiln.This amount of metal is so small as to not affect the operation of therotary kiln V and is so small as to not result in any material amount ofheat being transferred to the kiln shell. The principal por tion of thisshim 4t) is available so as to reinforce a kiln lining.

Obviously a number of other expedients besides those specifically shownin Figs. 4 and 5 of the drawing can be utilized so as to space a metalshim formed in accordance with this invention from the metal shell of arotary kiln; amongst these expedients is the use of a cardboard or othersimilar combustible material. In assembling a rotary kiln where none ofthe various spacing means illustrated in Figs. 3, 4 and 5 of the drawingare utilized, it is possible to position such a combustible materialbetween the metal shim employed and a metal shell of a rotary kiln asthe individual courses of brick are being installed. During use of akiln constructed in this manner, the combustible material will burn outafter the individual shims are rmly held in place. Equivalentnon-combusd tible spacers can, of course, be employed.

In Fig. 6 of the drawing there is shown a modied rotary kiln structure`60 of the invention which includes a metal shell 62 within which thereis positioned a lining composed of individual bricks 64 similar to thebricks 18 laid up in courses 766 extending in planes parallel to theaxis of the shell 62. Between these courses 66 there are located metalshims `68, each of which includes outer and inner edges 7) and 72. Tothe inner edges 72 there are attached small anges 74 serving to holdthese shims 68 so that the outer edges 70 are spaced from the shell 62.With this construction the adjacent edges 76 of the shims 68 arepositioned against one another, and are staggered as shown in Fig. 7 soas to provide as much reinforcement for the lining of the structure 60as possible.

If desired effective results can be created by providing a rotary kilnstructure 80 as indicated in Fig. 8 of the drawing. Since this structureis substantially identical With the structure 6) the individual parts ofit are designated by the primes of the same numerals previouslyemployed. In the stnucture 80 the shims 68 are formed so that each ofthese shims 68 is of approximately the same length `as one of the bricks64 and so that the edges 76 are not staggered as in Fig. 7.

In Fig. 9 of the drawing there is shown another modified shim 80 of theinvention having the form of a complete ring formed out of sheet iron orthe like so as to have an outer edge 82 and the inner edge 84. Smallmetal flanges 86 are attached to this inner edge 84 so as to engage theexposed surface of a brick lining 88 in a metal kiln shell 90 asindicated in Figs. l0 and 11. Thus, the anges 86 serve to position theouter edge 82 of the shim 80 away from the kiln shell 90 in order toaccomplish the results previously indicated. Various other means such asare indicated in the preceding to be the equivalent of flanges, such asthe flanges 86, can be substituted for these flanges. As will be.apparent in Figs. 10 and l1 the brick lining S8 is composed of rows orcourses of brick 92 located in planes transverse to the axis of the kilnshell 90.

Those skilled in the art to which this invention pertains will realizethat the shims 68 and 68 can be modified in the ways indicated indiscussing the shims 20, 30, and 40 and that these latter shims servesubstantially the same function as the former in a similar manner to theformer. The shims 68 and 68 may also be constructed so as to be held inplace by any of the means previously indicated. Thus, the flanges 74 and74 may be omitted and extensions, a perforated structure, or

combustible spacers as indicated may be employed with these shims 68 and68.

I claim:

1. A rotary kiln of the class described which includes: a cylindricalmetal shell located with its axis at an angle to the horizontal; alining composed of a single layer of brick, each of said brick being ofa substantially uniform composition throughout, said brick being locatedin courses within said shell, said courses being located so as to extendin planes perpendicular to the axis of said shell; and metal shimshaving arcuate inner and outer ends positioned between said courses ofbrick so as to space said courses from one another, each of said metalshims extending transversely of the axis of the kiln across a pluralityof the joints between successive individual bricks in said courses andbeing positioned Within said kiln so that the side edges of said shimsare located next to one another and so that the side edges of said shimsbetween adjacent courses of said brick are staggered with respect to oneanother, the principal portions 'of said shims being spacedfrom saidshell so as to restrict the transfer of heat to said shell through saidshims, and said shims being unattached with respect to said shell andfree to move relative to said shell.

2. A rotary kiln as detined in claim 1 wherein said metal shims arespaced from said shell and wherein said metal shims are held withrespect to said lining of brick by flange means formed on said shims,said flange means engaging the interior of said lining of brick.

3. A rotary kiln comprising: a cylindrical metal shell and a liningwithin said shell, at -least a portion of said lining including basicbricks each of which is of substantially uniform physical and chemicalcomposition throughout and each of which has a complete face in fullcontact with said metal shell, and a metal shim positioned between atleast one surface of each of said bricks and a surface of another ofsaid bricks with each of said shims being spaced away from said shell soas to restrict the transfer of heat to said shell through said shims.

4. A rotary kiln as deiined in claim 3 including llange means formed oneach of said metal shims and engaging the interior surface of saidlining of bricks.

5. A rotary kiln as defined in claim 3 wherein said metal shims areformed of metal plates, each of said metal plates including extensionsformed thereon engaging said shell so as to hold said metal plates outof contact with said shell.

6. A rotary kiln as deiined in claim 3 wherein said metal shims areformed in the shape of metal plates, each of said metal plates includinga perforate outer portion, said perforate outer portions engaging saidmetal shell so as to space the principal portions of said plates fromsaid metal shell.

7. A rotary kiln which includes: a cylindrical metal shell; a lining ofbasic bricks covering at least a portion of said shell, each of saidbricks being of substantially uniform physical and chemical compositionand having a complete face in full contact with said shell, said bricksbeing positioned in courses within said shell; metal shims positionedbetween said bricks in each of said courses, said shims serving to spacesaid brick within each course from one another, and said shims beingunattached with respect to said shell and regularly spaced away fromsaid shell so as to restrict the transfer of heat from the interior ofsaid kiln to said shell through said shims.

8. A rotary kiln which includes: a .cylindrical metal shell; a lining ofbasic bricks covering at least a portion of said shell, each of saidbricks being of substantially `uniform physical and chemical compositionand having a complete face in full contact with said shell, said bricksbeing positioned in courses within said shell; metal shims positionedbetween the bricks of adjacent courses, said shims serving to space saidcourses of brick from one another, and said shims being unattached withrespect to said shell and regularly spaced away from said shell so as torestrict the transfer of heat from the interior of said kiln to saidshell through said shims.

9. A rotary kiln which includes: a cylindrical metal shell located withits axis at an angle to the horizontal; a lining of bricks positioned incourses within at least a portion of said shell; and metal shimspositioned between said courses of bricks, each of said shims extendingtransversely of the axis of the kiln across a. plurality of the jointsbetween successive individual bricks in said courses, said metal shimsbeing unattached With respect to said shell and being free to move withrespect to said shell.

l0. A rotary kiln as dened in claim 9, wherein said courses extendcircumferentially of said kiln and wherein said shims are continuousmetal rings each extending completely around the interior of said shell.

ll. A rotary kiln which includes: a cylindrical metal shell located withits axis at an angle to the horizontal;

a lining of bricks positioned in courses within at least a portion ofsaid shell; and metal shims positioned between said courses of bricks,each of said shims extending transversely of the axis of the kiln acrossa plurality of the joints between successive individual bricks in saidcourses, said metal shims being unattached with respect to said shelland being free to move with respect to said shell, and said shims beingstaggered with respect to each other.

12. A rotary kiln which includes: a cylindrical metal shell located withits axis at an angle to the horizontal; a lining of bricks positioned incourses within at least ,a portion of said shell; and metal shimspositioned between said courses of bricks, each of said shims extendingtransversely of the axis of the kiln across a plurality of the jointsbetween successive individual bricks in said courses, said metal shimsbeing spaced away from and unattached with respect to said metal shelland being free to move relative to said shell.

13. A rotary kiln which includes: a cylindrical metal shell located withits axis at an angle to the horizontal; a lining of bricks covering atleast a portion of said shell, each of said bricks being ofsubstantially uniform composition and having a complete face in fullcontact with said shell, said bricks being positioned in courses withinsaid shell; and metal shims positioned between the bricks of adjacentcourses, each of said shims extending transversely of the axis of thekiln across a plurality of the joints between successive individualbricks in said courses, said metal shims being unattached with respectto said shell and being free to move with respect to said shell, saidshims being staggered with respect to each other, and said shims beingspaced away from said shell so as to restrict the transfer of heat fromthe interior of said kiln to said shell through said shims.

14. A rotary kiln which includes a cylindrical metal shell located withits axis at an angle to the horizontal; a lining of bricks positioned incourses within at least a portion of said shell; and continuous metalrings positioned between said courses of bricks, each of said ringsextending transversely of the axis of the kiln completely around theinterior of said kiln and across the joints between successiveindividual bricks in said courses, said rings being spaced away from andunattached with respect to said shell and being free to move withrespect to said shell.

15. A rotary kiln as delined in claim 1 wherein said metal shims areheld with respect to said lining of brick by extensions formed on saidshims, said extensions engaging the interior of said shell.

16. A rotary kiln as defined in claim 1 wherein said metal shims eachincludes a perforate outer portion engaging said shell, said perforateouter portions serving to hold said shims with respect to said lining ofbrick.

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